Such a device has been known from DOS 2,753,302. This conventional device is intended, in particular, for the separation of dust from flue gases; for this purpose, the device is installed between a boiler and a suction fan or a chimney. The conventional device comprises a housing with an untreated gas chamber and a pure gas duct located thereabove, as well as with a dust-collecting chamber arranged below the untreated gas chamber. Furthermore, the conventional device has several cyclone separators arranged in rows one behind the other and in side-by-side relationship or in stepwise fashion obliquely superimposed. The raw gas to be purified, especially to be subjected to dust removal, enters into these cyclone separators tangentially and flows as pure gas upwardly through pipes from the cyclone separators into the pure gas duct and from the latter through an outlet opening out of the device. The lower ends of the cyclone separators, in the device known from DOS 2,753,302, penetrate the lower boundary wall of the raw gas chamber and are open toward the dust-collecting chamber arranged therebelow.
It is known from DOS 2,150,733 to arrange several small cyclones in devices for dust separation.
Dust separation facilities having high separating efficiencies are prescribed for furnace plants and for other installations emitting dust-laden gases, within the scope of stricter environmental protection regulations. It is difficult with the known devices to maintain the prescribed limit values of residual dust load in the pure gas discharged from the installations.
Cyclone separators have been known from EP-A 398,864 and, respectively, Austrian Patent 392,924 wherein pure gas is discharged from the separating chamber via two dip pipes projecting into this chamber and being located in axial opposition. These separators with two dip pipes (separators with double dip pipe) are substantially more efficient than the cyclone separators suggested, for example, in DOS 2,753,302.